It started as a guerrilla street art project in Cambridge aimed at beginning a conversation. Then it quickly became something else, a grass-roots movement that spread quickly, because it requires no language and no explaining. You just have to consider two very similar images.

One image is the wheelchair symbol, which has become one of the most familiar icons in the world since it was introduced in 1968. The other is an edited version, with the human distinct from the chair, in an active position, with a feeling of forward movement.

In the three years since Sara Hendren, a Cambridge artist and writer who teaches at the Rhode Island School of Design, and Brian Glenney, an assistant professor of philosophy at Gordon College, began placing their version over the existing one, the Accessible Icon Project has gone from an artistic statement to a global movement.

Today, the symbol has been adopted by institutions as varied as the Jacksonville Jaguars of the NFL, the city of New York, and the Boys and Girls Club in South Boston. Recently, the Museum of Modern Art accepted the image into its permanent collection.

“It’s amazing how many people have discovered this project and then rallied behind it,” Hendren said. “People write to us from all over the world, and they say ‘I know exactly what you’re doing. You don’t even need to explain it.’ ”

The original goal of the project was to begin a dialogue about the way society views disability. They felt the old symbol was stiff, robotic, with the chair functioning as a part of, not a tool for, the human. The original icon was just a wheelchair until a later designer added a head in the form of a dot on the top of the chair back.

Hendren and Glenney call each other co-instigators, but their goal was never to instigate a movement. Others had already tried that, including a 1994 image by Brendan Murphy that was the inspiration for Hendren.

But so many have been adopting their symbol that they’ve begun the process of going through official channels to ask that their image be formally accepted as an alternative to the original. No one would be required to change current signs under their request.

Backers submitted a request to the Massachusetts Architectural Access Board, and it is there that the movement hit its first stumbling block. After months in subcommittee, the project received word through its attorney that the board is concerned about a financial conflict of interest.

Hendren and Glenney had gifted the commercial rights for the icon to Triangle, Inc., a Malden nonprofit group that has been working to empower individuals with disabilities since 1971. But the state expressed concern that the new icon could be a money-making venture for Triangle.

Triangle says that’s not their intention. They sell stickers and parking stencils on their website, but also provide free templates so that people can make their own, said Jeff Gentry, the senior director of community partnerships and program development at Triangle.

Terrel Harris, the communications director for the state’s Executive Office of Public Safety and Security, which oversees the board considering the new icon, refused to comment on the matter while it is in subcommittee.

For those involved in the Accessible Icon Project, they consider the stall at the state level to be a minor speed bump. There are many, like Hendren, who think that the idea’s real power still lies outside official channels. “You have to hang out in that space of provocation where you show rather than tell,” said Hendren, “where you don’t summarily deliver a solution. I’m interested in a whole constellation of questions that start with the symbol but don’t end there.”

Instead, advocates prefer to focus on the organic movement that has already led so many to adopt the icon, from a hospital in India to UMass-Amherst to the city of Malden, where Mayor Gary Christenson has committed to transitioning the city to the new icon, regardless of what the state says.

They point to the story of Brendon Hildreth, a 23-year-old from Reading who has cerebral palsy and hearing loss and uses a communication device. Hildreth had been volunteering at Triangle, but recently moved with his family to New Bern, N.C., so he could pursue his dream and attend community college. And there, he has become a one-man ambassador for the icon, using a Power Point presentation to single-handedly convince restaurants, institutions and entire towns to adopt the new symbol.

“He believes in the message of it,” said his mother, Darcy. “For him, it says ‘The disability is not a part of me. I have a disability. The disability doesn’t have me.’”

For his mother, she said that simple act of making the icon active rather than passive exemplifies the message she and her husband have long tried to instill in their son. “We’ve always told him, ‘Brendon, I’m sorry that your muscles don’t work, but that doesn’t excuse you. You have other abilities.’ And that’s what this symbol represents. Moving forward. Not letting a disability stop you.”